Printed wiring board and method for manufacturing printed wiring board

ABSTRACT

A printed wiring board includes a main substrate and a rising substrate. A support portion of the rising substrate is inserted into a slit in the main substrate. In a direction in which a plurality of first electrodes are aligned, a width of each of the plurality of first electrodes is larger than a width of each of a plurality of second electrodes, and the width of each of the plurality of second electrodes is arranged to fit within the width of each of the plurality of first electrodes.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/485,349, filed Aug. 12, 2019, which is a U.S. National PhaseApplication of International Application No. PCT/JP2017/035907, filedOct. 3, 2017, each incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a printed wiring board, and inparticular to a printed wiring board including a main substrate and arising substrate.

BACKGROUND ART

An electronic device having a rising substrate attached to a mainsubstrate is described, for example, in Japanese Patent No. 4314809 (PTL1). In this electronic device, an auxiliary substrate (rising substrate)is inserted into a slit provided in a mother substrate (main substrate),and terminal pads (electrodes) of the rising substrate are soldered toterminal pads (electrodes) of the main substrate.

CITATION LIST Patent Literature

PTL 1: Japanese Patent No. 4314809

SUMMARY OF INVENTION Technical Problem

In the electronic device having the rising substrate attached to themain substrate described in the above publication, misalignment betweenthe electrodes of the main substrate and the electrodes of the risingsubstrate may occur due to dimensional tolerances caused duringmanufacturing of the substrates. In this case, the amount of solder of asolder joint is smaller than that when the misalignment does not occur.Thus, rupture of the solder joint occurs in a short time due to a strainresulting from a temperature cycle under a usage environment.

The present invention has been made in view of the aforementionedproblem, and an object thereof is to provide a printed wiring boardcapable of suppressing occurrence of rupture of a solder joint in ashort time.

Solution to Problem

A printed wiring board of the present invention includes a mainsubstrate and a rising substrate. The main substrate has a top surface,a bottom surface, a slit penetrating from the top surface to the bottomsurface, and a plurality of first electrodes provided on the bottomsurface. The rising substrate has a support portion and a plurality ofsecond electrodes provided in the support portion and connected to theplurality of first electrodes, respectively, using solder. The supportportion of the rising substrate is inserted into the slit in the mainsubstrate. In a direction in which the plurality of first electrodes arealigned, a width of each of the plurality of first electrodes is largerthan a width of each of the plurality of second electrodes, and thewidth of each of the plurality of second electrodes is arranged to fitwithin the width of each of the plurality of first electrodes.

Advantageous Effects of Invention

According to the printed wiring board of the present invention, thewidth of each of the plurality of first electrodes is larger than thewidth of each of the plurality of second electrodes, and the width ofeach of the plurality of second electrodes is arranged to fit within thewidth of each of the plurality of first electrodes. Thus, a solder jointis reliably formed with the width of the second electrode. Therefore,this can prevent the amount of solder of the solder joint from beingdecreased because the width of the solder joint is smaller than thewidth of the second electrode. This can prevent occurrence of rupture ofthe solder joint in a short time due to a strain resulting from atemperature cycle under a usage environment.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view schematically showing a configuration inwhich a rising substrate is mounted in a main substrate in a firstembodiment of the present invention.

FIG. 2 is a cross sectional view schematically showing the configurationin which the rising substrate is mounted in the main substrate in thefirst embodiment of the present invention.

FIG. 3 is a bottom view schematically showing a configuration of themain substrate in the first embodiment of the present invention.

FIG. 4 is a front view schematically showing a configuration of therising substrate in the first embodiment of the present invention.

FIG. 5 is an enlarged perspective view showing the positional relationbetween a first electrode provided on the main substrate and a secondelectrode provided on the rising substrate in the first embodiment ofthe present invention.

FIG. 6 is a schematic view for illustrating a configuration of the mainsubstrate and the rising substrate having design values in the firstembodiment of the present invention.

FIG. 7 is a schematic view for illustrating a configuration of a slitand a support portion having design values in the first embodiment ofthe present invention.

FIG. 8 is a schematic view for illustrating a configuration in which therising substrate has a minimum dimension and the main substrate has amaximum dimension in the first embodiment of the present invention.

FIG. 9 is a schematic view for illustrating the slit and the supportportion in the configuration in which the rising substrate has theminimum dimension and the main substrate has the maximum dimension inthe first embodiment of the present invention.

FIG. 10 is a schematic cross sectional view for illustrating a methodfor manufacturing a printed wiring board in the first embodiment of thepresent invention.

FIG. 11 is a bottom view schematically showing a configuration of a mainsubstrate in a comparative example.

FIG. 12 is a schematic view for illustrating a configuration of the mainsubstrate and a rising substrate in the comparative example.

FIG. 13 is a schematic view for illustrating a configuration of the mainsubstrate and the rising substrate in the comparative example.

FIG. 14 is a schematic view for illustrating misalignment between afirst electrode and a second electrode in the comparative example.

FIG. 15 is a bottom view schematically showing a configuration of a mainsubstrate in a first variation of the first embodiment.

FIG. 16 is a front view schematically showing a configuration of arising substrate in the first variation of the first embodiment.

FIG. 17 is a bottom view schematically showing a configuration ofanother main substrate in the first variation of the first embodiment.

FIG. 18 is a front view schematically showing a configuration of anotherrising substrate in the first variation of the first embodiment.

FIG. 19 is an enlarged front view schematically showing a configurationof a main substrate and a rising substrate in a second variation of thefirst embodiment.

FIG. 20 is a bottom view schematically showing a configuration of a mainsubstrate in a third variation of the first embodiment.

FIG. 21 is a front view schematically showing a configuration of arising substrate in the third variation of the first embodiment.

FIG. 22 is an enlarged perspective view showing the positional relationbetween a first electrode provided on a main substrate and a secondelectrode provided on a rising substrate in a fourth variation of thefirst embodiment.

FIG. 23 is a perspective view schematically showing a configuration inwhich a rising substrate is mounted in a main substrate in a secondembodiment of the present invention.

FIG. 24 is a bottom view schematically showing a configuration of themain substrate in the second embodiment of the present invention.

FIG. 25 is a front view schematically showing a configuration of therising substrate in the second embodiment of the present invention.

FIG. 26 is a schematic view for illustrating a configuration of the mainsubstrate and the rising substrate having design values in the secondembodiment of the present invention.

FIG. 27 is a schematic view for illustrating a configuration of a slitand a support portion having design values in the second embodiment ofthe present invention.

FIG. 28 is a schematic view for illustrating a configuration in whichthe rising substrate has a maximum dimension and the main substrate hasa minimum dimension in the second embodiment of the present invention.

FIG. 29 is a schematic view for illustrating a configuration of the slitand the support portion in the configuration in which the risingsubstrate has the maximum dimension and the main substrate has theminimum dimension in the second embodiment of the present invention.

FIG. 30 is a schematic view for illustrating a configuration in whichthe rising substrate has a minimum dimension and the main substrate hasa maximum dimension in the second embodiment of the present invention.

FIG. 31 is a schematic view for illustrating a configuration of the slitand the support portion in the configuration in which the risingsubstrate has the minimum dimension and the main substrate has themaximum dimension in the second embodiment of the present invention.

FIG. 32 is a perspective view schematically showing a configuration inwhich a rising substrate is mounted in a main substrate in a thirdembodiment of the present invention.

FIG. 33 is a bottom view schematically showing a configuration of themain substrate in the third embodiment of the present invention.

FIG. 34 is a front view schematically showing a configuration of therising substrate in the third embodiment of the present invention.

FIG. 35 is a schematic view for illustrating a configuration of the mainsubstrate and the rising substrate having design values in the thirdembodiment of the present invention.

FIG. 36 is a schematic view for illustrating a configuration of a slitand a support portion having design values in the third embodiment ofthe present invention.

FIG. 37 is a schematic view for illustrating a configuration in whichthe rising substrate has a maximum dimension and the main substrate hasa minimum dimension in the third embodiment of the present invention.

FIG. 38 is a schematic view for illustrating a configuration of the slitand the support portion in the configuration in which the risingsubstrate has the maximum dimension and the main substrate has theminimum dimension in the third embodiment of the present invention.

FIG. 39 is a schematic view for illustrating another configuration ofthe slit and the support portion in the configuration in which therising substrate has the maximum dimension and the main substrate hasthe minimum dimension in the third embodiment of the present invention.

FIG. 40 is a schematic view for illustrating a configuration in whichthe rising substrate has a minimum dimension and the main substrate hasa maximum dimension in the third embodiment of the present invention.

FIG. 41 is a schematic view for illustrating a configuration of the slitand the support portion in the configuration in which the risingsubstrate has the minimum dimension and the main substrate has themaximum dimension in the third embodiment of the present invention.

FIG. 42 is a schematic view for illustrating another configuration ofthe slit and the support portion in the configuration in which therising substrate has the minimum dimension and the main substrate hasthe maximum dimension in the third embodiment of the present invention.

FIG. 43 is a view showing the amounts of solder forming electrode padsin Examples 1 and 2.

FIG. 44 is a front view schematically showing a configuration in a fifthvariation of the first embodiment.

FIG. 45 is a view schematically showing a structure to be compared withthe configuration in the fifth variation of the first embodiment.

FIG. 46 is a perspective view schematically showing a configuration inwhich a rising substrate is mounted in a main substrate in a fourthembodiment of the present invention.

FIG. 47 is a bottom view schematically showing a configuration of themain substrate in the fourth embodiment of the present invention.

FIG. 48 is a front view schematically showing a configuration of therising substrate in the fourth embodiment of the present invention.

FIG. 49 is a schematic view for illustrating a configuration of the mainsubstrate and the rising substrate having design values in the fourthembodiment of the present invention.

FIG. 50 is a schematic view for illustrating a configuration of a slitand a support portion having design values in the fourth embodiment ofthe present invention.

FIG. 51 is a schematic view for illustrating a configuration in whichthe rising substrate has a maximum dimension and the main substrate hasa minimum dimension in the fourth embodiment of the present invention.

FIG. 52 is a schematic view for illustrating a configuration of the slitand the support portion in the configuration in which the risingsubstrate has the maximum dimension and the main substrate has theminimum dimension in the fourth embodiment of the present invention.

FIG. 53 is a schematic view for illustrating a configuration in whichthe rising substrate has a minimum dimension and the main substrate hasa maximum dimension in the fourth embodiment of the present invention.

FIG. 54 is a schematic view for illustrating a configuration of the slitand the support portion in the configuration in which the risingsubstrate has the minimum dimension and the main substrate has themaximum dimension in the fourth embodiment of the present invention.

FIG. 55 is a schematic cross sectional view for illustrating a methodfor manufacturing the printed wiring board in the first embodiment ofthe present invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be describedbased on the drawings.

First Embodiment

A configuration of a printed wiring board 10 in a first embodiment ofthe present invention will be described with reference to FIGS. 1 to 5.Printed wiring board 10 in the present embodiment is a three-dimensionalprinted wiring board. FIG. 1 is a perspective view showing printedwiring board 10 in the present embodiment. FIG. 2 is a cross sectionalview showing a state where a rising substrate 2 is mounted in a mainsubstrate 1. FIG. 3 is a bottom view showing a bottom surface 1 b ofmain substrate 1. FIG. 4 is a front view showing a front surface 2 a ofrising substrate 2.

As shown in FIGS. 1 and 2, printed wiring board 10 in the presentembodiment includes main substrate 1 and rising substrate 2. Mainsubstrate 1 has a top surface 1 a, bottom surface 1 b, a slit 11, and aplurality of first electrodes 11 a. Rising substrate 2 is connected tomain substrate 1 to rise from top surface 1 a of main substrate 1.Rising substrate 2 has front surface 2 a, a rear surface 2 b, a bodyportion 21, a support portion 22, and a plurality of second electrodes22 a.

Slit 11 in main substrate 1 is provided to penetrate from top surface 1a to bottom surface 1 b of main substrate 1. Slit 11 is provided at aposition corresponding to support portion 22 of rising substrate 2. Slit11 may be provided by press working using a metal mold.

As shown in FIGS. 2 and 3, the plurality of first electrodes 11 a areprovided on bottom surface 1 b of main substrate 1. The plurality offirst electrodes 11 a are arranged to be aligned in a longitudinaldirection of slit 11 at regular spacings. The plurality of firstelectrodes 11 a are arranged with slit 11 being sandwiched therebetweenin a short direction of slit 11. That is, the plurality of firstelectrodes 11 a are arranged on both of one side and the other side inthe short direction of slit 11.

Main substrate 1 is made of a common printed wiring board material.Specifically, main substrate 1 is made of, for example, CEM-3 (Compositeepoxy material-3), which is a laminate produced by using a glassnonwoven fabric impregnated with a fire-resistant epoxy resin for a coreof a base material, and using a prepreg formed of a glass fabric and anepoxy resin for surfaces to provide reinforced strength.

As shown in FIGS. 1 and 4, body portion 21 of rising substrate 2 isconnected to support portion 22. Body portion 21 protrudes on one sideand the other side of support portion 22. Body portion 21 protrudes onboth sides in a longitudinal direction of support portion 22. Bodyportion 21 protrudes on both sides of slit 11 in the longitudinaldirection of slit 11. Electronic components are mounted in body portion21. These electronic components are a power semiconductor device, atransformer, and the like, for example.

Support portion 22 of rising substrate 2 is provided to protrudedownward from body portion 21 at a lower portion of rising substrate 2.The plurality of second electrodes 22 a are provided in support portion22. The plurality of second electrodes 22 a are arranged to be alignedin the longitudinal direction of support portion 22 at regular spacings.

As shown in FIGS. 1 and 2, support portion 22 of rising substrate 2 isinserted into slit 11 in main substrate 1. The plurality of secondelectrodes 22 a are arranged at positions corresponding to the pluralityof first electrodes 11 a, respectively. The plurality of secondelectrodes 22 a are provided on both of front surface 2 a and rearsurface 2 b. The plurality of second electrodes 22 a are connected tothe plurality of first electrodes 11 a, respectively, using solder 6. Bysoldering the plurality of second electrodes 22 a to first electrodes 11a, rising substrate 2 is electrically connected to main substrate 1.

Rising substrate 2 is made of a common printed wiring board material.Specifically, rising substrate 2 is made of, for example, CEM-3, whichis a laminate produced by using a glass nonwoven fabric impregnated witha fire-resistant epoxy resin for a core of a base material, and using aprepreg formed of a glass fabric and an epoxy resin for surfaces toprovide reinforced strength.

As shown in FIGS. 1 and 5, in a direction in which the plurality offirst electrodes 11 a are aligned, one width of a width Mw of each ofthe plurality of first electrodes 11 a and a width Sw of each of theplurality of second electrodes 22 a is larger than the other width. Theother width is arranged to fit within the one width of width Mw of eachof the plurality of first electrodes 11 a and width Sw of each of theplurality of second electrodes 22 a. That is, in the short direction ofslit 11, each of the plurality of first electrodes 11 a overlaps witheach of the plurality of second electrodes 22 a by a smaller width ofthe widths of first electrode 11 a and second electrode 22 a. In otherwords, width Sw of second electrode 22 a does not extend beyond width Mwof first electrode 11 a.

In the present embodiment, width Mw of each of the plurality of firstelectrodes 11 a is larger than width Sw of each of the plurality ofsecond electrodes 22 a. In addition, width Sw of each of the pluralityof second electrodes 22 a is arranged to fit within width Mw of each ofthe plurality of first electrodes 11 a. That is, in the short directionof slit 11, each of the plurality of second electrodes 22 a overlapswith each of the plurality of first electrodes 11 a by width Sw ofsecond electrode 22 a.

The width of first electrode 11 a of main substrate 1, the width ofsecond electrode 22 a of rising substrate 2, and the like will bedescribed in further detail with reference to FIGS. 6 to 9.

As shown in FIGS. 6 and 7, the width and the position of each of firstelectrode 11 a and second electrode 22 a are designed such that, basedon a certain determined origin O, the center (center in a widthdirection) of first electrode 11 a matches the center of secondelectrode 22 a. Origin O is, for example, a position where supportportion 22 overlaps with slit 11 on a rear side in a flow direction. Thewhite arrow in FIG. 6 indicates the flow direction, that is, a directionin which main substrate 1 moves. It should be noted that the whitearrows in the drawings subsequent to FIG. 6 also indicate the flowdirection (the direction in which main substrate 1 moves).

On this occasion, the width of first electrode 11 a is larger than thewidth of second electrode 22 a such that an overlapping width betweenfirst electrode 11 a and second electrode 22 a is equal to the width ofsecond electrode 22 a, even in a combination of a case where slit 11 hasa maximum length in the longitudinal direction and a case where supportportion 22 has a minimum length in the longitudinal direction,considering the influence of misalignment which may occur due todimensional tolerances.

Here, details of each design value thereof will be described.

First, a case where the substrates have design values (nominal values)will be described with reference to FIGS. 6 and 7.

As shown in FIG. 6, width Sw of second electrode 22 a and width Mw offirst electrode 11 a have a relation Mw>Sw. Portions of rising substrate2 have dimensions a, b, and c, where a is a width of body portion 21protruding from support portion 22 on one end side of rising substrate2, b is a width of support portion 22, and c is a width of body portion21 protruding from support portion 22 on the other end side of risingsubstrate 2. Slit 11 in main substrate 1 has a dimension B in thelongitudinal direction.

First electrode 11 a and second electrode 22 a are designed such that,when rising substrate 2 is caused to flow by jet solder during flowsoldering and contacts slit 11 at an X portion, the center of firstelectrode 11 a of main substrate 1 matches the center of secondelectrode 22 a of rising substrate 2, at a position having a distance αfrom the origin. First electrodes 11 a and second electrodes 22 a aredesigned to be aligned at a pitch P. On this occasion, as shown in FIG.7, a gap between slit 11 and support portion 22 is indicated by D. Itshould be noted that X portion is a portion where main substrate 1contacts rising substrate 2.

Next, a case where rising substrate 2 has a minimum dimension and mainsubstrate 1 has a maximum dimension will be described with reference toFIGS. 8 and 9.

Values of plus/minus tolerances in processing rising substrate 2 andslit 11 are indicated by ts and tm, respectively. On this occasion, eachportion has a dimension as shown in FIG. 8.

Here, a tolerance in forming the electrodes during manufacturing of thesubstrates is neglected, and it is assumed that the values of α, Sw, Mw,and P remain unchanged. Thus, when rising substrate 2 is caused to flowby a jet during flow soldering and contacts slit 11 at X portion, thecenter of second electrode 22 a of rising substrate 2 matches the centerof first electrode 11 a of main substrate 1, at a position havingdistance α from origin O.

On this occasion, the gap is indicated by D shown in FIG. 9.

When the value of (Mw−Sw)/2 is more than or equal to the value ofD+ts+tm, first electrode 11 a can reliably overlap with second electrode22 a by the width of Sw even if rising substrate 2 is misaligned withinslit 11.

Here, it is generally satisfactory to assume that the tolerance informing the electrodes during manufacturing of the substrates, which isneglected above, is more than or equal to 0.05 mm.

Thus, when the above relation is expressed by an expression, the presentembodiment satisfies an expression (1):(Mw−Sw)/2≥D+ts+tm≥0.05  (1).

In addition, in the present embodiment, pitch P between the plurality offirst electrodes 11 a and between the plurality of second electrodes 22a, one larger width Mw and the other smaller width Sw of each of theplurality of first electrodes 11 a and each of the plurality of secondelectrodes 22 a, and value D obtained by subtracting the length ofsupport portion 22 from the length of slit 11 in a direction in whichslit 11 extends have a relation P/2>(Mw−Sw)/2≥D.

Next, a method for manufacturing the printed wiring board in the presentembodiment will be described with reference to FIGS. 2, 10, and 55.

As shown in FIG. 2, with support portion 22 being vertically insertedinto slit 11, first electrodes 11 a of main substrate 1 and secondelectrodes 22 a of rising substrate 2 are soldered with each other. Forexample, the electrodes of main substrate 1 and rising substrate 2transported by a conveyor with rising substrate 2 being attached to mainsubstrate 1 are soldered with each other by a flow soldering method inwhich the electrodes are immersed in a molten solder jet and aresoldered. Thereby, first electrodes 11 a are soldered and fixed tosecond electrodes 22 a.

Specifically, as shown in FIG. 10, molten solder 6 stored in a solderbath 200 jets upward from a flow soldering nozzle 201, as a drive forceof a motor 202 is transmitted to a propeller 204 via a motor shaft 203and rotates propeller 204. On this occasion, it is often performed tojet molten solder 6 with different shapes from a plurality of flowsoldering nozzles 201, as shown in FIG. 55, to obtain stable solderjoints. Bottom surface 1 b of main substrate 1 is arranged above flowsoldering nozzles 201. Bottom surface 1 b of main substrate 1 isimmersed in jet solder. Thereby, the plurality of second electrodes 22 aare soldered to the plurality of first electrodes 11 a, respectively.

Next, the function and effect in the present embodiment will bedescribed as compared with a comparative example.

A printed wiring board in the comparative example will be described withreference to FIGS. 11 to 14. As shown in FIG. 11, in the printed wiringboard in the comparative example, a tapered portion 110 is providedwithin slit 11. Due to this tapered portion 110, slit 11 partially has asmaller opening dimension. Rising substrate 2 is held in slit 11 in mainsubstrate 1 by being supported by tapered portion 110. In this state,first electrodes 11 a are soldered to second electrodes 22 a by flowsoldering.

As shown in FIGS. 12 and 13, in the printed wiring board in thecomparative example, width Mw of each of first electrodes 11 a of mainsubstrate 1 is equal to width Sw of each of second electrodes 22 a ofrising substrate 2. In a case where the substrates have design values,the center of first electrode 11 a overlaps with the center of secondelectrode 22 a. However, in a case where dimensional tolerances arecaused during manufacturing of the substrates, misalignment occurs in anoverlapping width W between first electrode 11 a and second electrode 22a, as shown in FIG. 14.

During flow soldering, the printed wiring board is immersed in moltensolder from a front end of the printed wiring board and is soldered,while being transported by a conveyor. The molten solder jetted from thesolder bath adheres to first electrode 11 a and second electrode 22 a,wettably spreads, and solidifies, thereby forming a solder joint. Onthis occasion, the amount of solder forming the solder joint is largeras overlapping width W between first electrode 11 a and second electrode22 a is larger, and the amount of solder forming the solder joint issmaller as overlapping width W is smaller.

When the printed wiring board is assembled into a product aftercompletion of soldering, and is exposed to a temperature cycle under ausage environment after operation, a strain is repeatedly generated in asolder joint to alleviate thermal stress caused by the difference inthermal expansion coefficient between rising substrate 2 and mainsubstrate 1. Due to this strain, the solder joint eventually has fatiguefailure. When the amount of solder forming the solder joint betweenrising substrate 2 and main substrate 1 is small, a life until thesolder joint has fatigue failure becomes shorter than that when theamount of solder is large. Through the evaluation by the inventors,there has been obtained a result that, when the overlapping widthbetween the electrode of rising substrate 2 and the electrode of mainsubstrate 1 increases by 1.5 times, the effect of improving the lifeincreases by about 6 times or more.

Therefore, in the printed wiring board in the comparative example, whena solder joint is formed with small overlapping width W due tooccurrence of misalignment between first electrode 11 a and secondelectrode 22 a, the amount of solder is smaller than that in the casewhere the substrates have the design values. Thus, when the printedwiring board is exposed to the temperature cycle under the usageenvironment, the solder joint may have fatigue failure in a short time.

In contrast, according to printed wiring board 10 in the presentembodiment, one width of width Mw of each of the plurality of firstelectrodes 11 a and width Sw of each of the plurality of secondelectrodes 22 a is larger than the other width, and the other width isarranged to fit within the one width of width Mw of each of theplurality of first electrodes 11 a and width Sw of each of the pluralityof second electrodes 22 a. Thus, even when a maximum dimensionaltolerance as shown in FIG. 8 is caused relative to the design valuesshown in FIG. 6 and misalignment occurs between first electrode 11 a andsecond electrode 22 a, first electrode 11 a can reliably overlap withsecond electrode 22 a by a smaller width of width Mw of first electrode11 a and width Sw of second electrode 22 a. Thereby, a solder joint isreliably formed with the smaller width of the width of first electrode11 a and the width of second electrode 22 a. Therefore, this can preventthe amount of solder of the solder joint from being decreased becausethe width of the solder joint is smaller than the smaller width of thewidth of first electrode 11 a and the width of second electrode 22 a.Thereby, a solder joint including a fillet with a fixed volume can beformed. Accordingly, a sufficient amount of solder can be secured, andthus a printed wiring board securing high reliability can be provided.

In addition, the accuracy of manufacturing tolerances during processingof the substrates is different for each substrate manufacturer. With theconfiguration in the present embodiment, any substrate manufacturer canfabricate printed wiring boards with suppressed variations inreliability, and thus can provide printed wiring boards having improvedquality.

In addition, printed wiring board 10 in the present embodiment has therelation P/2>(Mw−Sw)/2≥D. Thereby, first electrode 11 a can reliablyoverlap with second electrode 22 a by width Sw of second electrode 22 a.

Next, various variations of the present embodiment will be describedwith reference to FIGS. 15 to 22. It should be noted that, since thevarious variations of the present embodiment include the same componentsas those in the present embodiment described above unless otherwisespecified, identical elements will be designated by the same referencenumerals and the description thereof will not be repeated. Also in thesevarious variations of the present embodiment, the same effect as that ofthe present embodiment described above can be obtained.

A first variation of the present embodiment will be described.

Although the present embodiment has described a case where one slit 11is provided in main substrate 1 and one support portion 22 is providedin rising substrate 2, two or more slits 11 and two or more supportportions 22 may be provided.

As shown in FIGS. 15 and 16, in the first variation the presentembodiment, for example, two slits 11 are provided in main substrate 1and two support portions 22 are provided in rising substrate 2. Further,as shown in FIGS. 17 and 18, three slits 11 may be provided in mainsubstrate 1 and three support portions 22 may be provided in risingsubstrate 2,

According to the first variation of the first embodiment, by inserting aplurality of support portions 22 into a plurality of slits 11, risingsubstrate 2 is supported in main substrate 1 by the plurality of slits11 and the plurality of support portions 22. Thereby, rising substrate 2can be stably supported in main substrate 1.

Next, a second variation of the present embodiment will be described.

As shown in FIG. 19, in the second variation of the present embodiment,at least one of a symbol ink and a solder resist is arranged between theplurality of second electrodes 22 a. Specifically, bridge preventionlines 30 using at least one of a symbol ink and a solder resist areprovided. It should be noted that main substrate 1 is indicated by abroken line in FIG. 19 for convenience of description.

The symbol ink is a symbol ink mainly composed of a common acrylic-basedor epoxy-based resin. Specific examples of the symbol ink includeUSI-210W manufactured by Tamura Kaken, S-100W manufactured by Taiyo Ink,and the like. The symbol ink is formed by screen printing (a printingmethod in which holes are provided in a mesh screen itself and an ink istransferred therethrough), or an ink jet method.

When misalignment occurs between first electrode 11 a and secondelectrode 22 a, a solder bridge may occur due to a narrow gap betweenthe electrodes. In particular, when a solder bridge occurs at anoverlapping portion between rising substrate 2 and main substrate 1, itis impossible to repair the solder bridge without removing mainsubstrate 1.

In the second variation of the present embodiment, since at least one ofa symbol ink and a solder resist is arranged between the plurality ofsecond electrodes 22 a, occurrence of a solder bridge between theplurality of second electrodes 22 a can be prevented.

Further, whether soldering is good or poor can be determined by matchingthe amount of protrusion of rising substrate 2 from main substrate 1 toallowable dimensions of floating and inclination of rising substrate 2,as shown in FIG. 19. Specifically, when bridge prevention lines 30 areexposed above and below main substrate 1, it can be determined thatsoldering is good. On the other hand, when soldering is performed withrising substrate 2 protruding from main substrate 1 by more than theallowable dimension of floating due to an insert error of risingsubstrate 2 or a solder jet, bridge prevention lines 30 are not exposedbelow main substrate 1, and thus it can be determined that soldering ispoor. In addition, when soldering is performed with rising substrate 2being inclined relative to main substrate 1 by more than the allowabledimension of inclination due to an insert error of rising substrate 2 ora solder jet, bridge prevention lines 30 are exposed in differentamounts, and thus it can be determined that soldering is poor.Therefore, inspection can be facilitated.

Next, a third variation of the present embodiment will be described.

As shown in FIG. 20, in the third variation of the present embodiment, afirst relief-processed portion 41 is provided at each of four corners ofslit 11 along top surface 1 a of main substrate 1. Each of four firstrelief-processed portions 41 has an arc shape spreading toward theoutside of slit 11 along top surface 1 a of main substrate 1.

In addition, as shown in FIG. 21, second relief-processed portions 42are provided at a connection portion between support portion 22 and bodyportion 21 on one side and the other side of support portion 22 ofrising substrate 2. That is, second relief-processed portions 42 arerespectively provided on both sides of support portion 22 of risingsubstrate 2. Second relief-processed portion 42 on the one side ofsupport portion 22 has an arc shape spreading toward the other side ofsupport portion 22. Second relief-processed portion 42 on the other sideof support portion 22 has an arc shape spreading toward the one side ofsupport portion 22.

According to the third variation of the present embodiment, since firstrelief-processed portion 41 has an arc shape, angles at the four cornersof slit 11 are removed. This can secure mutual contact between mainsubstrate 1 and rising substrate 2. Further, since firstrelief-processed portion 41 has an arc shape, it has a small stressintensity factor. This can prevent occurrence of a crack in the portionprovided with first relief-processed portion 41 due to vibration and thelike.

In addition, since second relief-processed portion 42 has an arc shape,angles at the connection portion between support portion 22 and bodyportion 21 are removed. This can secure mutual contact between mainsubstrate 1 and rising substrate 2. Further, since secondrelief-processed portion 42 has an arc shape, it has a small stressintensity factor. This can prevent occurrence of a crack in the portionprovided with second relief-processed portion 42 due to vibration andthe like.

Next, a fourth variation of the present embodiment will be described.

Although the present embodiment has described a case where width Mw offirst electrode 11 a is larger than width Sw of second electrode 22 a,width Sw of second electrode 22 a may be larger than width Mw of firstelectrode 11 a.

As shown in FIG. 22, in the fourth variation of the present embodiment,width Sw of each of the plurality of second electrodes 22 a is largerthan width Mw of each of the plurality of first electrodes 11 a. Inaddition, width Mw of each of the plurality of first electrodes 11 a isarranged to fit within width Sw of each of the plurality of secondelectrodes 22 a. That is, in the short direction of slit 11, each of theplurality of first electrodes 11 a overlaps with each of the pluralityof second electrodes 22 a by the width of each of the plurality of firstelectrodes 11 a.

Furthermore, the inventors have confirmed through experiments that, whenfirst electrode 11 a is larger than second electrode 22 a, the amount ofsolder of a solder joint is larger than that when second electrode 22 ais larger than first electrode 11 a.

Next, other variations will be described.

Although CEM-3 is exemplified as a material for main substrate 1 andrising substrate 2 in the present embodiment described above, othermaterials may be used for main substrate 1 and rising substrate 2. Forexample, an FR-4 (Flame Retardant Type 4) base material formed byimpregnating a glass fiber cloth with an epoxy resin, a paper phenolsubstrate formed by impregnating a paper insulator with a phenol resin,a ceramic substrate formed by simultaneously firing a wiring conductorand a ceramic base material, or the like may be used. In addition,substrates made of different materials may be combined, in such a mannerthat the material for rising substrate 2 is CEM-3 and the material formain substrate 1 is FR-4.

Further, although the present embodiment has described a case where slit11 in main substrate 1 is provided by press working using a metal mold,slit 11 may be provided by cutting using a drill or a router.

Further, although the present embodiment has described a case whererising substrate 2 is mounted in main substrate 1 by the flow solderingmethod, rising substrate 2 may be mounted in main substrate 1 by aso-called a point flow method, which is a method of individually jettingmolten solder to predetermined soldering points using nozzles,respectively.

Furthermore, in a fifth variation of the present embodiment, as shown inFIG. 44, when support portion 22 of rising substrate 2 is inserted intoslit 11 in main substrate 1, the plurality of second electrodes 22 aextend to a height of the top surface of main substrate 1. Since thelength of second electrodes 22 a (height position of upper ends ofsecond electrodes 22 a) reaches top surface 1 a of main substrate 1 orextends thereabove, it is possible to increase the area wetted bysolder, and achieve a structure which can hold as much solder aspossible. In this case, it is possible to increase the volume forming afillet, when compared with a case where the length of second electrodes22 a does not reach top surface 1 a of main substrate 1 as shown in FIG.45. Therefore, a sufficient amount of solder can be secured, and thusprinted wiring board 10 securing high reliability can be provided.

Second Embodiment

A second embodiment of the present invention includes the samecomponents as those in the first embodiment of the present inventiondescribed above, unless otherwise specified. Thus, identical elementswill be designated by the same reference numerals, and the descriptionthereof will not be repeated.

A configuration of printed wiring board 10 in the second embodiment ofthe present invention will be described with reference to FIGS. 23 to25.

As shown in FIGS. 23 and 24, main substrate 1 has a first auxiliary slit12 and two first auxiliary female electrodes 12 a. First auxiliary slit12 is provided to penetrate from top surface 1 a to bottom surface 1 bof main substrate 1. First auxiliary slit 12 is arranged on one side ofslit 11. First auxiliary slit 12 is arranged to be linearly aligned withslit 11 in the longitudinal direction of slit 11. First auxiliary slit12 is provided at a position corresponding to a first auxiliary supportportion 23 described later.

Two first auxiliary female electrodes 12 a are provided on bottomsurface 1 b of main substrate 1. Two first auxiliary female electrodes12 a are arranged with first auxiliary slit 12 being sandwichedtherebetween in a short direction of first auxiliary slit 12.

As shown in FIGS. 23 and 25, rising substrate 2 has first auxiliarysupport portion 23 and two first auxiliary male electrodes 23 a. Firstauxiliary support portion 23 is provided to protrude downward from bodyportion 21 at the lower portion of rising substrate 2. Two firstauxiliary male electrodes 23 a are provided in first auxiliary supportportion 23. Two first auxiliary male electrodes 23 a are provided onboth of front surface 2 a and rear surface 2 b of rising substrate 2.

The surface area of first auxiliary female electrode 12 a is larger thanthe surface area of each of the plurality of first electrodes 11 a. Thesurface area of first auxiliary male electrode 23 a is larger than thesurface area of each of the plurality of second electrodes 22 a.

First auxiliary support portion 23 is inserted into first auxiliary slit12. In this state, two first auxiliary male electrodes 23 a are solderedto two first auxiliary female electrodes 12 a, respectively. Supportportion 22 is arranged to be spaced from an entire inner peripheralsurface of slit 11. Dimensions of support portion 22 and slit 11 in thelongitudinal direction of slit 11 are respectively larger thandimensions of first auxiliary support portion 23 and first auxiliaryslit 12 in the longitudinal direction of slit 11.

The width of first electrode 11 a of main substrate 1, the width ofsecond electrode 22 a of rising substrate 2, and the like will bedescribed in further detail with reference to FIGS. 26 to 31.

As shown in FIGS. 26 and 27, the width and the position of each of firstelectrode 11 a and second electrode 22 a are designed such that, basedon a certain determined origin O, the center of first electrode 11 amatches the center of second electrode 22 a. Origin O is, for example, aposition where first auxiliary support portion 23 overlaps with firstauxiliary slit 12 on a rear side in a flow direction.

In any of a combination in which rising substrate 2 has a maximumdimension and main substrate 1 has a minimum dimension and a combinationin which rising substrate 2 has a minimum dimension and main substrate 1has a maximum dimension, which are caused by dimensional tolerances,support portion 22 does not contact slit 11 even if rising substrate 2is misaligned within slit 11 during mounting.

In any of the combination in which rising substrate 2 has the maximumdimension and main substrate 1 has the minimum dimension and thecombination in which rising substrate 2 has the minimum dimension andmain substrate 1 has the maximum dimension, the electrode of mainsubstrate 1 reliably overlaps with the electrode of rising substrate 2by any of the width of the electrode of main substrate 1 and the widthof the electrode of rising substrate 2, even if rising substrate 2 ismisaligned within slit 11 during mounting.

Here, details of each design value thereof will be described.

First, a case where the substrates have design values (nominal values)will be described with reference to FIGS. 26 and 27.

As shown in FIG. 26, width Mw of first electrode 11 a and width Sw ofsecond electrode 22 a have a relation Mw>Sw. Portions of risingsubstrate 2 have dimensions a, b, c, and d, where a is a width of firstauxiliary support portion 23, b is a spacing between first auxiliarysupport portion 23 and support portion 22, c is a width of supportportion 22, and d is a width of body portion 21 protruding from supportportion 22 on the other end side of rising substrate 2. Portions of mainsubstrate 1 have dimensions A, B, and C, where A is a width of firstauxiliary slit 12, B is a spacing between first auxiliary slit 12 andslit 11, and C is a width of slit 11.

First electrode 11 a and second electrode 22 a are designed such that,when rising substrate 2 is caused to flow by jet solder during flowsoldering and first auxiliary support portion 23 contacts firstauxiliary slit 12 at an X portion, the center of first electrode 11 a ofmain substrate 1 matches the center of second electrode 22 a of risingsubstrate 2, at a position having distance α from the origin. Firstelectrodes 11 a and second electrodes 22 a are designed to be aligned atpitch P. On this occasion, as shown in FIG. 27, a gap between firstauxiliary slit 12 and first auxiliary support portion 23 is indicated byF. Gaps between slit 11 and support portion 22 on one side and the otherside are indicated by G and H.

Next, a case where rising substrate 2 has the maximum dimension and mainsubstrate 1 has the minimum dimension will be described with referenceto FIGS. 28 and 29.

Values of plus/minus tolerances in processing rising substrate 2 andslit 11 are indicated by ts and tm, respectively. On this occasion, eachportion has a dimension as shown in FIG. 28.

Here, the tolerance in forming the electrodes during manufacturing ofthe substrates is neglected, and it is assumed that the values of α, Sw,Mw, and P remain unchanged. Thus, when rising substrate 2 is caused toflow by a jet during flow soldering and contacts first auxiliary slit 12at X portion, the center of second electrode 22 a of rising substrate 2matches the center of first electrode 11 a of main substrate 1, at aposition having distance α from origin O.

On this occasion, the gaps are indicated by F, G, and H shown in FIG.29.

When the value of G+ts+tm is more than the value of F−tm−ts, endportions of support portion 22 have no contact within slit 11 even ifrising substrate 2 is misaligned within slit 11.

Further, when the value of (Mw−Sw)/2 is more than or equal to the valueof F−tm−ts, first electrode 11 a can reliably overlap with secondelectrode 22 a by the width of Sw even if rising substrate 2 ismisaligned within slit 11.

When the above relation is expressed by an expression, an expression (2)is obtained:G+ts+tm>(Mw−Sw)/2≥F−tm−ts  (2).

Next, a case where rising substrate 2 has the minimum dimension and mainsubstrate 1 has the maximum dimension will be described with referenceto FIGS. 30 and 31.

On this occasion, each portion has a dimension as shown in FIG. 30.

Here, the tolerance in forming the electrodes during manufacturing ofthe substrates is neglected, and it is assumed that the values of α, Sw,Mw, and P remain unchanged. Thus, when rising substrate 2 is caused toflow by a jet during flow soldering and contacts first auxiliary slit 12at X portion, the center of second electrode 22 a of rising substrate 2matches the center of first electrode 11 a of main substrate 1, at aposition having distance α from origin O.

On this occasion, the gaps are indicated by F, G, and H shown in FIG.31.

When the value of G−ts−tm is more than the value of F+tm+ts, endportions of support portion 22 have no contact within slit 11 even ifrising substrate 2 is misaligned within slit 11.

Further, when the value of (Mw−Sw)/2 is more than or equal to the valueof F+tm+ts, first electrode 11 a can reliably overlap with secondelectrode 22 a by the width of Sw even if rising substrate 2 ismisaligned within slit 11.

When the above relation is expressed by an expression, an expression (3)is obtained:G−ts−tm>(Mw−Sw)/2≥F+tm+ts  (3).

In order to satisfy both expressions (2) and (3), it is only necessaryto satisfy expression (3).

Here, it is generally satisfactory to assume that the tolerance informing the electrodes during manufacturing of the substrates, which isneglected above, is more than or equal to 0.05 mm.

Thus, when the above relation is expressed by an expression, the presentembodiment satisfies an expression (4):G−ts−tm>(Mw−Sw)/2≥F+tm+ts≥0.05  (4).

Next, a method for manufacturing the printed wiring board in the presentembodiment will be described with reference to FIG. 23.

As shown in FIG. 23, support portion 22 and first auxiliary supportportion 23 are vertically inserted into slit 11 and first auxiliary slit12, respectively. In this state, first electrodes 11 a are soldered tosecond electrodes 22 a, and first auxiliary female electrodes 12 a aresoldered to first auxiliary male electrodes 23 a.

For example, the electrodes of main substrate 1 and rising substrate 2transported by a conveyor with rising substrate 2 being attached to mainsubstrate 1 are soldered with each other by a flow soldering method inwhich the electrodes are immersed in a molten solder jet and aresoldered. Thereby, first electrodes 11 a are soldered and fixed tosecond electrodes 22 a, and first auxiliary female electrodes 12 a aresoldered and fixed to first auxiliary male electrodes 23 a.

Next, the function and effect of the present embodiment will bedescribed.

Also in the present embodiment, the same effect as that of the firstembodiment described above can be obtained.

In addition, in printed wiring board 10 in the present embodiment,support portion 22 is arranged to be spaced from the entire innerperipheral surface of slit 11. As shown in FIG. 27, in the state aftermounting, both ends of support portion 22 on one side and the other sidedo not contact slit 11. Thus, a strain generated in second electrodes 22a in support portion 22 is equalized. Thereby, a life until a solderjoint ruptures is prolonged, when compared with a case where one end ofsupport portion 22 contacts slit 11. It should be noted that theinventors have confirmed through experiments that, when the ends ofsupport portion 22 do not contact slit 11, the life is prolonged abouttwice when compared with the case where one end of support portion 22contacts slit 11. Therefore, a printed wiring board having highreliability until a solder joint ruptures can be provided.

In addition, in printed wiring board 10 in the present embodiment, thedimensions of support portion 22 and slit 11 in the longitudinaldirection of slit 11 are respectively larger than the dimensions offirst auxiliary support portion 23 and first auxiliary slit 12 in thelongitudinal direction of slit 11. This can prevent incorrect assemblyin which support portion 22 and first auxiliary support portion 23 arereversely inserted into first auxiliary slit 12 and slit 11 when risingsubstrate 2 is inserted into main substrate 1. Therefore, printed wiringboard 10 excellent in assembling property can be provided.

In addition, in printed wiring board 10 in the present embodiment, thesurface area of first auxiliary female electrode 12 a is larger than thesurface area of each of the plurality of first electrodes 11 a, and thesurface area of first auxiliary male electrode 23 a is larger than thesurface area of each of the plurality of second electrodes 22 a. Thus,bonding strength can be enhanced by increasing the amount of solder of asolder joint.

Next, various variations of the present embodiment will be described.Although the present embodiment has described a case where firstauxiliary support portion 23 and first auxiliary slit 12 are arranged ona front side in the flow direction, first auxiliary support portion 23and first auxiliary slit 12 may be arranged on a rear side in the flowdirection.

Third Embodiment

A third embodiment of the present invention includes the same componentsas those in the first and second embodiments of the present inventiondescribed above, unless otherwise specified. Thus, identical elementswill be designated by the same reference numerals, and the descriptionthereof will not be repeated.

A configuration of printed wiring board 10 in the third embodiment ofthe present invention will be described with reference to FIGS. 32 to34.

As shown in FIGS. 32 and 33, main substrate 1 has a second auxiliaryslit 13 and two second auxiliary female electrodes 13 a. Secondauxiliary slit 13 is provided to penetrate from top surface 1 a tobottom surface 1 b of main substrate 1. Second auxiliary slit 13 isarranged to be linearly aligned with slit 11 and first auxiliary slit 12in the longitudinal direction of slit 11. First auxiliary slit 12 andsecond auxiliary slit 13 are arranged on both sides of slit 11. Secondauxiliary slit 13 is provided at a position corresponding to a secondauxiliary support portion 24 described later.

Two second auxiliary female electrodes 13 a are provided on bottomsurface 1 b of main substrate 1. Two second auxiliary female electrodes13 a are arranged with second auxiliary slit 13 being sandwichedtherebetween in a short direction of second auxiliary slit 13.

As shown in FIGS. 32 and 34, rising substrate 2 has second auxiliarysupport portion 24 and two second auxiliary male electrodes 24 a. Secondauxiliary support portion 24 is provided to protrude downward from bodyportion 21 at the lower portion of rising substrate 2. First auxiliarysupport portion 23 and second auxiliary support portion 24 are arrangedon both sides of support portion 22. Two second auxiliary maleelectrodes 24 a are provided in second auxiliary support portion 24. Twosecond auxiliary male electrodes 24 a are provided on both of frontsurface 2 a and rear surface 2 b of rising substrate 2.

The surface area of first auxiliary female electrode 12 a is larger thanthe surface area of each of the plurality of first electrodes 11 a. Thesurface area of first auxiliary male electrode 23 a is larger than thesurface area of each of the plurality of second electrodes 22 a. Thesurface area of second auxiliary female electrode 13 a is larger thanthe surface area of each of the plurality of first electrodes 11 a. Thesurface area of second auxiliary male electrode 24 a is larger than thesurface area of each of the plurality of second electrodes 22 a.

Second auxiliary support portion 24 is inserted into second auxiliaryslit 13. In this state, two second auxiliary male electrodes 24 a aresoldered to two second auxiliary female electrodes 13 a, respectively.Support portion 22 is arranged to be spaced from an entire innerperipheral surface of slit 11. Dimensions of first auxiliary supportportion 23 and first auxiliary slit 12 in the longitudinal direction ofslit 11 are respectively larger than dimensions of second auxiliarysupport portion 24 and second auxiliary slit 13 in the longitudinaldirection of slit 11.

The width of first electrode 11 a of main substrate 1, the width ofsecond electrode 22 a of rising substrate 2, and the like will bedescribed in further detail with reference to FIGS. 35 to 42.

As shown in FIGS. 35 and 36, the width and the position of each of firstelectrode 11 a and second electrode 22 a are designed such that, basedon a certain determined origin O, the center of first electrode 11 amatches the center of second electrode 22 a. Origin O is, for example, aposition where second auxiliary support portion 24 overlaps with secondauxiliary slit 13 on a rear side in a flow direction.

In any of a combination in which rising substrate 2 has a maximumdimension and main substrate 1 has a minimum dimension and a combinationin which rising substrate 2 has a minimum dimension and main substrate 1has a maximum dimension, which are caused by dimensional tolerances,support portion 22 does not contact slit 11, and the electrode of mainsubstrate 1 reliably overlaps with the electrode of rising substrate 2by any of the width of the electrode of main substrate 1 and the widthof the electrode of rising substrate 2, even if rising substrate 2 ismisaligned within slit 11 during mounting.

Here, details of each design value thereof will be described.

First, a case where the substrates have design values (nominal values)will be described with reference to FIGS. 35 and 36.

As shown in FIG. 35, width Mw of first electrode 11 a and width Sw ofsecond electrode 22 a have a relation Mw>Sw. Portions of risingsubstrate 2 have dimensions a, b, c, d, and e, where a is a width ofsecond auxiliary support portion 24, b is a spacing between secondauxiliary support portion 24 and support portion 22, c is a width ofsupport portion 22, d is a width of first auxiliary support portion 23,and e is a spacing between first auxiliary support portion 23 and secondauxiliary support portion 24.

Portions of main substrate 1 have dimensions A, B, C, D, and E, where Ais a width of second auxiliary slit 13, B is a spacing between secondauxiliary slit 13 and slit 11, C is a width of slit 11, D is a width offirst auxiliary slit 12, and E is a spacing between first auxiliary slit12 and second auxiliary slit 13.

First electrode 11 a and second electrode 22 a are designed such that,when rising substrate 2 is caused to flow by a jet during flow solderingand second auxiliary support portion 24 contacts second auxiliary slit13 at an X portion, the center of first electrode 11 a of main substrate1 matches the center of second electrode 22 a of rising substrate 2, ata position having distance α from the origin. First electrodes 11 a andsecond electrodes 22 a are designed to be aligned at pitch P. On thisoccasion, as shown in FIG. 36, a gap between second auxiliary slit 13and second auxiliary support portion 24 is indicated by F. Gaps betweenslit 11 and support portion 22 on one side and the other side areindicated by G and H. A gap between first auxiliary slit 12 and firstauxiliary support portion 23 is indicated by I and J.

Next, a case where rising substrate 2 has the maximum dimension and mainsubstrate 1 has the minimum dimension will be described with referenceto FIGS. 37 to 39. Values of plus/minus tolerances in processing risingsubstrate 2 and slit 11 are indicated by ts and tm, respectively. Onthis occasion, each portion has a dimension as shown in FIG. 37.

Here, the tolerance in forming the electrodes during manufacturing ofthe substrates is neglected, and it is assumed that the values of α, Sw,Mw, and P remain unchanged. Thus, when rising substrate 2 is caused toflow by a jet during flow soldering and contacts second auxiliary slitat X portion, the center of second electrode 22 a of rising substrate 2matches the center of first electrode 11 a of main substrate 1, at aposition having distance α from origin O.

On this occasion, the gaps are indicated by F, G, H, I, and J shown inFIG. 38.

When the value of J−2tm−2ts is 0, the value of H+2ts+2tm is more than 0,and the value of G+tm+ts is more than 0 as shown in FIG. 39, secondauxiliary support portion 24 contacts second auxiliary slit 13 at Xportion on one side, and first auxiliary support portion 23 contactsfirst auxiliary slit 12 at an X portion on the other side. Further, onthis occasion, end portions of support portion 22 do not contact slit11.

When the above relation is expressed by expressions, expressions (5),(6), and (7) are obtained:J−2tm−2ts=0  (5);H+2ts+2tm>0  (6);G+tm+ts>0  (7).

Next, a case where rising substrate 2 has the minimum dimension and mainsubstrate 1 has the maximum dimension will be described with referenceto FIGS. 40 to 42. On this occasion, each portion has a dimension asshown in FIG. 40.

On this occasion, the gaps are indicated by F, G, H, I, and J shown inFIG. 41.

When the value of I+ts+tm is 0, the value of H−2ts−2tm is more than 0,and the value of G−tm−ts is more than 0 as shown in FIGS. 41 and 42,second auxiliary support portion 24 contacts second auxiliary slit 13 atX portion on one side, and first auxiliary support portion 23 contactsfirst auxiliary slit 12 at an X portion on the other side. Further, onthis occasion, end portions of support portion 22 do not contact slit11.

When the above relation is expressed by expressions, expressions (8),(9), and (10) are obtained:I+tm+ts=0  (8);H−2ts−2tm>0  (9);G−tm−ts>0  (10).

Here, it is generally satisfactory to assume that the tolerance informing the electrodes during manufacturing of the substrates, which isneglected above, is more than or equal to 0.05 mm.

Thus, as long as the value of (Mw−Sw)/2 is more than or equal to 0.05mm, first electrode 11 a can reliably overlap with second electrode 22 aby the width of Sw.

When the above relation is expressed by an expression, an expression(11) is obtained:(Mw−Sw)/2≥0.05  (11).

Thus, in order to satisfy all expressions (5) to (11), it is onlynecessary to satisfy expressions (5), (8), (9), (10), and (11).

Next, a method for manufacturing the printed wiring board in the presentembodiment will be described with reference to FIG. 32.

As shown in FIG. 32, support portion 22, first auxiliary support portion23, and second auxiliary support portion 24 are vertically inserted intoslit 11, first auxiliary slit 12, and second auxiliary slit 13,respectively. In this state, first electrodes 11 a are soldered tosecond electrodes 22 a, first auxiliary female electrodes 12 a aresoldered to first auxiliary male electrodes 23 a, and second auxiliaryfemale electrodes 13 a are soldered to second auxiliary male electrodes24 a.

For example, the electrodes of main substrate 1 and rising substrate 2transported by a conveyor with rising substrate 2 being attached to mainsubstrate 1 are soldered with each other by a flow soldering method inwhich the electrodes are immersed in a molten solder jet and aresoldered. Thereby, first electrodes 11 a are soldered and fixed tosecond electrodes 22 a, first auxiliary female electrodes 12 a aresoldered and fixed to first auxiliary male electrodes 23 a, and secondauxiliary female electrodes 13 a are soldered and fixed to secondauxiliary male electrodes 24 a.

Next, the function and effect of the present embodiment will bedescribed.

Also in the present embodiment, the same effect as that of the firstembodiment described above can be obtained.

In addition, in printed wiring board 10 in the present embodiment, thedimensions of first auxiliary support portion 23 and first auxiliaryslit 12 in the longitudinal direction of slit 11 are respectively largerthan the dimensions of second auxiliary support portion 24 and secondauxiliary slit 13 in the longitudinal direction of slit 11. This canprevent incorrect assembly in which first auxiliary support portion 23and second auxiliary support portion 24 are reversely inserted intosecond auxiliary slit 13 and first auxiliary slit 12 when risingsubstrate 2 is inserted into main substrate 1. Therefore, printed wiringboard 10 excellent in assembling property can be provided.

In addition, also in printed wiring board 10 in the present embodiment,support portion 22 is arranged to be spaced from the entire innerperipheral surface of slit 11. Thus, a strain generated in secondelectrodes 22 a in support portion 22 is equalized. Thereby, a lifeuntil a solder joint ruptures is prolonged, when compared with a casewhere one end of support portion 22 contacts slit 11. Therefore, printedwiring board 10 having high reliability until a solder joint rupturescan be provided.

In addition, in printed wiring board 10 in the present embodiment, thesurface area of first auxiliary female electrode 12 a is larger than thesurface area of each of the plurality of first electrodes 11 a, and thesurface area of first auxiliary male electrode 23 a is larger than thesurface area of each of the plurality of second electrodes 22 a.Further, the surface area of second auxiliary female electrode 13 a islarger than the surface area of each of the plurality of firstelectrodes 11 a, and the surface area of second auxiliary male electrode24 a is larger than the surface area of each of the plurality of secondelectrodes 22 a. Thus, bonding strength can be enhanced by increasingthe amount of solder of a solder joint.

In addition, second auxiliary female electrode 13 a of main substrate 1and second auxiliary male electrode 24 a of rising substrate 2 areelectrodes provided at both ends where the maximum strain is applied.Thus, a strain generated due to the difference in linear expansioncoefficient between main substrate 1 and rising substrate 2 can bereduced. Therefore, all solder joints provided in support portion 22 canhave a prolonged life. Accordingly, printed wiring board 10 havingfurther improved reliability can be obtained.

In addition, a defect of misalignment between first electrode 11 a ofmain substrate 1 and second electrode 22 a of rising substrate 2 canalso be prevented by improving a self alignment effect obtained byenlarging second auxiliary female electrode 13 a of main substrate 1 andsecond auxiliary male electrode 24 a of rising substrate 2. Therefore, aprinted wiring board having improved quality can be obtained. The selfalignment effect is a function in which misalignment of an electroniccomponent mounted on an electrode is corrected by the surface tension ofmolten solder on the electrode. As the electrode is larger, the surfacetension is larger, resulting in an improved self alignment effect.

Fourth Embodiment

A fourth embodiment of the present invention includes the samecomponents as those in the first embodiment of the present inventiondescribed above, unless otherwise specified. Thus, identical elementswill be designated by the same reference numerals, and the descriptionthereof will not be repeated.

A configuration of printed wiring board 10 in the fourth embodiment ofthe present invention will be described with reference to FIGS. 46 to54.

As shown in FIGS. 46 and 47, main substrate 1 has first auxiliary slit12 and two first auxiliary female electrodes 12 a. First auxiliary slit12 is provided to penetrate from top surface 1 a to bottom surface 1 bof main substrate 1. First auxiliary slit 12 is arranged on one side ofa first slit 43 and a second slit 45. First auxiliary slit 12 isarranged to be linearly aligned with a first slit 43 and a second slit45 in the longitudinal direction of a first slit 43 and a second slit45. First auxiliary slit 12 is provided at a position corresponding tofirst auxiliary support portion 23 described later.

Two first auxiliary female electrodes 12 a are provided on bottomsurface 1 b of main substrate 1. Two first auxiliary female electrodes12 a are arranged with first auxiliary slit 12 being sandwichedtherebetween in the short direction of first auxiliary slit 12.

As shown in FIGS. 46 and 48, rising substrate 2 has first auxiliarysupport portion 23 and two first auxiliary male electrodes 23 a. Firstauxiliary support portion 23 is provided to protrude downward from bodyportion 21 at the lower portion of rising substrate 2. Two firstauxiliary male electrodes 23 a are provided in first auxiliary supportportion 23. Two first auxiliary male electrodes 23 a are provided onboth of front surface 2 a and rear surface 2 b of rising substrate 2.

The surface area of first auxiliary female electrode 12 a is larger thanthe surface area of each of the plurality of first electrodes 11 a. Inthe present embodiment, first electrodes 11 a include first slit femaleelectrodes 43 a and second slit female electrodes 45 a. The surface areaof first auxiliary male electrode 23 a is larger than the surface areaof each of the plurality of second electrodes 22 a. In the presentembodiment, second electrodes 22 a include first support portion maleelectrodes 44 a and second support portion male electrodes 46 a.

First auxiliary support portion 23 is inserted into first auxiliary slit12. In this state, two first auxiliary male electrodes 23 a are solderedto two first auxiliary female electrodes 12 a, respectively. A firstsupport portion 44 is arranged to be spaced from an entire innerperipheral surface of first slit 43. A second support portion 46 isarranged to be spaced from an entire inner peripheral surface of secondslit 45. Dimensions of first support portion 44 and first slit 43 in alongitudinal direction of first slit 43 are respectively larger thandimensions of first auxiliary support portion 23 and first auxiliaryslit 12 in the longitudinal direction of first slit 43. Dimensions ofsecond support portion 46 and second slit 45 in the longitudinaldirection of first slit 43 are respectively larger than the dimensionsof first auxiliary support portion 23 and first auxiliary slit 12 in thelongitudinal direction of first slit 43.

The width of first support portion male electrode 44 a and secondsupport portion male electrode 46 a of rising substrate 2, the width offirst slit female electrode 43 a and second slit female electrode 45 aof main substrate 1, and the like will be described in further detailwith reference to FIGS. 49 to 54.

As shown in FIGS. 49 and 50, the width and the position of each of firstsupport portion male electrode 44 a and first slit female electrode 43 aare designed such that, based on a certain determined origin O, thecenter of first support portion male electrode 44 a matches the centerof first slit female electrode 43 a. At the same time, the width and theposition of each of second support portion male electrode 46 a andsecond slit female electrode 45 a are designed such that, based oncertain determined origin O, the center of second support portion maleelectrode 46 a matches the center of second slit female electrode 45 a.Origin O is, for example, a position where first auxiliary supportportion 23 overlaps with first auxiliary slit 12 on a rear side in aflow direction.

In any of a combination in which rising substrate 2 has a maximumdimension and main substrate 1 has a minimum dimension and a combinationin which rising substrate 2 has a minimum dimension and main substrate 1has a maximum dimension, which are caused by dimensional tolerances,first support portion 44 does not contact first slit 43, and at the sametime, second support portion 46 does not contact second slit 45, even ifrising substrate 2 is misaligned within a first slit 43 and a secondslit 45 during mounting.

In any of the combination in which rising substrate 2 has the maximumdimension and main substrate 1 has the minimum dimension and thecombination in which rising substrate 2 has the minimum dimension andmain substrate 1 has the maximum dimension, the electrode of mainsubstrate 1 reliably overlaps with the electrode of rising substrate 2by any of the width of the electrode of main substrate 1 and the widthof the electrode of rising substrate 2, even if rising substrate 2 ismisaligned within a first slit 43 and a second slit 45 during mounting.

Here, details of each design value thereof will be described.

First, a case where the substrates have design values (nominal values)will be described with reference to FIGS. 49 and 50.

As shown in FIG. 49, width Mw of first slit female electrode 43 a andsecond slit female electrode 45 a and width Sw of first support portionmale electrode 44 a and second support portion male electrode 46 a havea relation Mw>Sw. Portions of rising substrate 2 have dimensions a, b,c, d, e, and f, where a is a width of first auxiliary support portion23, b is a spacing between first auxiliary support portion 23 and firstsupport portion 44, c is a width of first support portion 44, d is aspacing between first support portion 44 and second support portion 46,e is a width of second support portion 46, and f is a width of bodyportion 21 protruding from second support portion 46 on the other endside of rising substrate 2. Here, c and e are set to less than or equalto 65 mm. Portions of main substrate 1 have dimensions A, B, C, D, andE, where A is a width of first auxiliary slit 12, B is a spacing betweenfirst auxiliary slit 12 and first slit 43, C is a width of first slit43, D is a spacing between first slit 43 and second slit 45, and E is awidth of second slit 45.

First slit female electrode 43 a and first support portion maleelectrode 44 a are designed such that, when rising substrate 2 is causedto flow by jet solder during flow soldering and first auxiliary supportportion 23 contacts first auxiliary slit 12 at an X portion, the centerof first slit female electrode 43 a of main substrate 1 matches thecenter of first support portion male electrode 44 a of rising substrate2, at a position having distance α from the origin. Further, second slitfemale electrode 45 a and second support portion male electrode 46 a aredesigned such that, on this occasion, the center of second slit femaleelectrode 45 a of main substrate 1 matches the center of second supportportion male electrode 46 a of rising substrate 2. First slit femaleelectrodes 43 a and first support portion male electrodes 44 a aredesigned to be aligned at pitch P. Further, second slit femaleelectrodes 45 a and second support portion male electrodes 46 a are alsodesigned to be aligned at pitch P. On this occasion, as shown in FIG.50, a gap between first auxiliary slit 12 and first auxiliary supportportion 23 is indicated by F. Gaps between first slit 43 and firstsupport portion 44 on one side and the other side are indicated by G andH. Gaps between second slit 45 and second support portion 46 on one sideand the other side are indicated by I and J.

Next, a case where rising substrate 2 has the maximum dimension and mainsubstrate 1 has the minimum dimension will be described with referenceto FIGS. 51 and 52.

Values of plus/minus tolerances in processing rising substrate 2 and afirst slit 43 and a second slit 45 are indicated by ts and tm,respectively. On this occasion, each portion has a dimension as shown inFIG. 51.

Here, the tolerance in forming the electrodes during manufacturing ofthe substrates is neglected, and it is assumed that the values of α, Sw,Mw, and P remain unchanged. Thus, when rising substrate 2 is caused toflow by a jet during flow soldering and contacts first auxiliary slit 12at X portion, the center of first support portion male electrode 44 a ofrising substrate 2 matches the center of first slit female electrode 43a of main substrate 1, at a position having distance α from origin O.Further, on this occasion, the center of second slit female electrode 45a of main substrate 1 matches the center of second support portion maleelectrode 46 a of rising substrate 2.

On this occasion, the gaps are indicated by F, G, H, I, and J shown inFIG. 52.

When the values of G+ts+tm and I+3ts+3tm are more than the value ofF−tm−ts, end portions of first support portion 44 have no contact withinfirst slit 43, and at the same time, end portions of second supportportion 46 have no contact within second slit 45, even if risingsubstrate 2 is misaligned within first slit 43 and second slit 45.

Further, when the value of (Mw−Sw)/2 is more than or equal to the valueof F−tm−ts, first electrode 11 a can reliably overlap with secondelectrode 22 a by the width of Sw even if rising substrate 2 ismisaligned within a first slit 43 and a second slit 45.

When the above relation is expressed by expressions, expressions (12)and (13) are obtained:G+ts+tm>(Mw−Sw)/2≥F−tm−ts  (12);I+3ts+3tm>(Mw−Sw)/2≥F−tm−ts  (13).

Next, a case where rising substrate 2 has the minimum dimension and mainsubstrate 1 has the maximum dimension will be described with referenceto FIGS. 53 and 54.

On this occasion, each portion has a dimension as shown in FIG. 53.

Here, the tolerance in forming the electrodes during manufacturing ofthe substrates is neglected, and it is assumed that the values of α, Sw,Mw, and P remain unchanged. Thus, when rising substrate 2 is caused toflow by a jet during flow soldering and contacts first auxiliary slit 12at X portion, the center of first support portion male electrode 44 a ofrising substrate 2 matches the center of first slit female electrode 43a of main substrate 1, at a position having distance α from origin O.Further, on this occasion, the center of second slit female electrode 45a of main substrate 1 matches the center of second support portion maleelectrode 46 a of rising substrate 2.

On this occasion, the gaps are indicated by F, G, and H shown in FIG.54.

When the value of G−ts−tm and the value of I−3tm−3ts are more than thevalue of F+tm+ts, end portions of first support portion 44 and secondsupport portion 46 (support portion 22) have no contact within a firstslit 43 and a second slit 45 even if rising substrate 2 is misalignedwithin a first slit 43 and a second slit 45.

Further, when the value of (Mw−Sw)/2 is more than or equal to the valueof F+tm+ts, first electrode 11 a can reliably overlap with secondelectrode 22 a by the width of Sw even if rising substrate 2 ismisaligned within a first slit 43 and a second slit 45.

When the above relation is expressed by expressions, expressions (14)and (15) are obtained:G−ts−tm>(Mw−Sw)/2≥F+tm+ts  (14);I−3tm−3ts>(Mw−Sw)/2≥F+tm+ts  (15).

In order to satisfy both expressions (12) and (14), it is only necessaryto satisfy expression (14).

In order to satisfy both expressions (13) and (15), it is only necessaryto satisfy expression (15).

Here, it is generally satisfactory to assume that the tolerance informing the electrodes during manufacturing of the substrates, which isneglected above, is more than or equal to 0.05 mm.

Thus, when the above relation is expressed by expressions, the presentembodiment satisfies expressions (16) and (17):G−ts−tm>(Mw−Sw)/2≥F+tm+ts≥0.05  (16);I−3tm−3ts>(Mw−Sw)/2≥F+tm+ts≥0.05  (17).

Next, a method for manufacturing the printed wiring board in the presentembodiment will be described with reference to FIG. 46.

As shown in FIG. 46, first support portion 44, second support portion46, and first auxiliary support portion 23 are vertically inserted intofirst slit 43, second slit 45, and first auxiliary slit 12,respectively. In this state, first slit female electrodes 43 a aresoldered to first support portion male electrodes 44 a, second slitfemale electrodes 45 a are soldered to second support portion maleelectrodes 46 a, and first auxiliary female electrodes 12 a are solderedto first auxiliary male electrodes 23 a.

For example, the electrodes of main substrate 1 and rising substrate 2transported by a conveyor with rising substrate 2 being attached to mainsubstrate 1 are soldered with each other by a flow soldering method inwhich the electrodes are immersed in a molten solder jet and aresoldered. Thereby, first slit female electrodes 43 a are soldered andfixed to first support portion male electrodes 44 a, second slit femaleelectrodes 45 a are soldered and fixed to second support portion maleelectrodes 46 a, and first auxiliary female electrodes 12 a are solderedand fixed to first auxiliary male electrodes 23 a.

Next, the function and effect of the present embodiment will bedescribed.

Also in the present embodiment, the same effect as those of the first tothird embodiments described above can be obtained.

In addition, in printed wiring board 10 in the present embodiment, thedimension of first slit 43 and the dimension of second slit 45 are setto less than or equal to 65 mm. In this case, warping of main substrate1 due to heat input during immersion in flow solder can be prevented,and thus a solder joint having a larger volume can be formed. Thereby, alife until the solder joint ruptures is prolonged. It should be notedthat the inventors have confirmed through experiments that, when thedimensions of first slit 43 and second slit 45 are set to less than orequal to 65 mm, the life is prolonged about twice or more when comparedwith a case where the dimensions thereof are set to less than or equalto 90 mm. Therefore, a printed wiring board having high reliabilityuntil a solder joint ruptures can be provided.

In addition, in printed wiring board 10 in the present embodiment, thesurface area of first auxiliary female electrode 12 a is larger than thesurface area of each of the plurality of first electrodes 11 a, and thesurface area of first auxiliary male electrode 23 a is larger than thesurface area of each of the plurality of second electrodes 22 a. Thus,bonding strength can be enhanced by increasing the amount of solder of asolder joint.

Next, various variations of the present embodiment will be described.Although the present embodiment has described a case where firstauxiliary support portion 23 and first auxiliary slit 12 are arranged ona front side in the flow direction, first auxiliary support portion 23and first auxiliary slit 12 may be arranged on a rear side in the flowdirection.

In addition, other variations of the present embodiment will bedescribed. Although the present embodiment has described a case wheretwo slits are provided in main substrate 1 and two support portions areprovided in rising substrate 2, two or more slits and two or moresupport portions may be provided.

EXAMPLE

Hereinafter, an example of the present invention will be described.Since the present example includes the same components as those in thefirst to third embodiments of the present invention described aboveunless otherwise specified, identical elements will be designated by thesame reference numerals, and the description thereof will not berepeated.

First, regarding Examples 1 and 2 of the present invention, the amountof solder forming each electrode pad was measured.

TABLE 1 Mw (mm) Sw (mm) Example 1 1.3 1.6 Example 2 1.6 1.3

As shown in Table 1, in Example 1, width Mw of each of the plurality offirst electrodes 11 a is 1.3 mm, and width Sw of the plurality of secondelectrodes 22 a is 1.6 mm. That is, width Mw of each of the plurality offirst electrodes 11 a is smaller than width Sw of each of the pluralityof second electrodes 22 a.

In addition, in Example 2, width Mw of each of the plurality of firstelectrodes 11 a is 1.6 mm, and width Sw of the plurality of secondelectrodes 22 a is 1.3 mm. That is, width Mw of each of the plurality offirst electrodes 11 a is larger than width Sw of each of the pluralityof second electrodes 22 a.

Further, width Mw of each of the plurality of first electrodes 11 a inExample 1 is equal to width Sw of the plurality of second electrodes 22a in Example 2. In addition, width Sw of each of the plurality of secondelectrodes 22 a in Example 1 is equal to width Mw of each of theplurality of first electrodes 11 a in Example 2.

It should be noted that, in Examples 1 and 2, the base material, thesolder composition, the length of the rising substrate, and the slit inthe main substrate are identical. Specifically, the solder compositionis Sn-3.0Ag-0.5Cu.

FIG. 43 shows the volumes (mm³) of amounts of solder forming electrodepads (PAD01 to PAD13) in each of Examples 1 and 2. As shown in FIG. 43,it was found that the amount of solder forming each electrode pad inExample 2 was larger than that in Example 1. Thereby, it was found thatthe amount of solder forming each electrode pad is larger when width Mwof each of the plurality of first electrodes 11 a is larger than widthSw of each of the plurality of second electrodes 22 a.

This is considered to be because of the following reason. When width Swof the electrode of a sub substrate is shorter, the exposed surface areaof the electrode of the sub substrate is smaller. This can suppress thesolder adhering to the electrodes of the substrates from being taken outby a solder jet in the direction in which the substrates move, when thesubstrates leave a flow bath.

Next, the situation of rupture in a vapor phase temperature cycle testwas inspected under a condition in which temperature was changed from−55° C. to +125° C.

TABLE 2 Number of NG Samples Number of (in which rupture occurredSamples in less than 2,000 cycles) Example 1 28 3 Example 2 28 0

As shown in Table 2, the number of samples is 28 in both Examples 1 and2. The number of samples in which rupture occurred in less than 2000cycles is referred to as the number of NG samples. As shown in Table 2,the number of NG samples in Example 2 was smaller than that inExample 1. Therefore, it was found that the life in Example 2 is longerthan that in Example 1.

Accordingly, as the amount of solder forming a solder joint becomeslarger, the life until the solder joint ruptures can be prolonged. Inaddition, when width Mw of the first electrode is larger than width Swof the second electrode, the amount of solder forming the solder jointbetween the electrodes becomes larger. Therefore, to prolong the life ofthe solder joint, it is preferable that width Mw of the first electrodeis larger than width Sw of the second electrode.

Furthermore, effects other than those described above will be described.By adopting the present embodiment in which the width of either secondelectrode 22 a or first electrode 11 a is shortened, it is possible toprevent a bridge induced by the misalignment of rising substrate 2within the slit during soldering. This is because, by shortening thewidth of one electrode, the one electrode can keep a distance from anelectrode of the other substrate adjacent to an electrode to which theone electrode is to be soldered.

In contrast, when both the width of second electrode 22 a and the widthof first electrode 11 a are lengthened and first electrodes 11 a andsecond electrodes 22 a are aligned at the same pitch, the distancebetween one electrode and an electrode of the other substrate adjacentto an electrode to which the one electrode is to be soldered becomesshorter, and thereby a bridge is easily generated. This phenomenon issignificant when the pitch between the electrodes is shortened forgreater density. Therefore, by adopting the configuration shown in thepresent embodiment, a bridge can be suppressed and the pitch between theelectrodes can be shortened, which can also contribute to greaterdensity.

It should be understood that the embodiments disclosed herein areillustrative and non-restrictive in every respect. The scope of thepresent invention is defined by the scope of the claims, rather than thedescription above, and is intended to include any modifications withinthe scope and meaning equivalent to the scope of the claims.

REFERENCE SIGNS LIST

1: main substrate; 1 a: top surface; 1 b: bottom surface; 2: risingsubstrate; 2 a: front surface; 2 b: rear surface; 10: printed wiringboard; 11: slit; 11 a: first electrode; 12: first auxiliary slit; 12 a:first auxiliary female electrode; 13: second auxiliary slit; 13 a:second auxiliary female electrode; 21: body portion; 22: supportportion; 22 a: second electrode; 23: first auxiliary support portion; 23a: first auxiliary male electrode; 24: second auxiliary support portion;24 a: second auxiliary male electrode; 30: bridge prevention line; 41:first relief-processed portion; 42: second relief-processed portion; 43:first slit; 43 a: first slit female electrode; 44: first supportportion; 44 a: first support portion male electrode; 45: second slit; 45a: second slit female electrode; 46: second support portion; 46 a:second support portion male electrode.

The invention claimed is:
 1. A printed wiring board comprising: a mainsubstrate having a top surface, a bottom surface, a slit penetratingfrom the top surface to the bottom surface, and a plurality of firstelectrodes provided on the bottom surface; and a rising substrate havinga support portion and a plurality of second electrodes provided in thesupport portion and connected to the plurality of first electrodes,respectively, using solder, the support portion of the rising substratebeing inserted into the slit in the main substrate, in a direction inwhich the plurality of first electrodes are aligned, a width of each ofthe plurality of first electrodes being larger than a width of each ofthe plurality of second electrodes, the width of each of the pluralityof second electrodes being arranged to fit within the width of each ofthe plurality of first electrodes, each of the plurality of secondelectrodes of the rising substrate being inserted into the slit in themain substrate, the solder being arranged between the rising substrateand an inner peripheral surface of the slit in the main substratewherein, with the support portion of the rising substrate being insertedinto the slit in the main substrate, the plurality of first electrodesand the plurality of second electrodes are connected using solder, andthe solder is formed on the bottom surface of the main substrate.
 2. Theprinted wiring board according to claim 1, wherein the support portionis arranged to be spaced from an entirety of the inner peripheralsurface of the slit.
 3. The printed wiring board according to claim 1,wherein at least one of a symbol ink and a solder resist is arrangedbetween the plurality of second electrodes.
 4. The printed wiring boardaccording to claim 1, wherein a first relief-processed portion isprovided at each of four corners of the slit along the top surface ofthe main substrate, and the first relief-processed portion has an arcshape spreading toward an outside of the slit along the top surface. 5.The printed wiring board according to claim 1, wherein the risingsubstrate includes a body portion connected to the support portion andprotruding on one side and another side of the support portion, secondrelief-processed portions are provided at a connection portion betweenthe support portion and the body portion on the one side and the otherside of the support portion, the second relief-processed portion on theone side has an arc shape spreading toward the other side, and thesecond relief-processed portion on the other side has an arc shapespreading toward the one side.
 6. The printed wiring board according toclaim 1, wherein a pitch P between the plurality of first electrodes andbetween the plurality of second electrodes, one larger width Mw andanother smaller width Sw of each of the plurality of first electrodesand each of the plurality of second electrodes, and a value D obtainedby subtracting a length of the support portion from a length of the slitin a direction in which the slit extends have a relationP/2>(Mw−Sw)/2≥D.
 7. The printed wiring board according to claim 1,wherein, with the support portion of the rising substrate being insertedinto the slit in the main substrate, the plurality of second electrodesextend to a height of the top surface of the main substrate.
 8. Theprinted wiring board according to claim 1, wherein two slits and twosupport portions are provided.
 9. The printed wiring board according toclaim 1, wherein the main substrate has a first auxiliary slitpenetrating from the top surface to the bottom surface, and two firstauxiliary female electrodes provided on the bottom surface, the firstauxiliary slit is arranged to be linearly aligned with the slit in alongitudinal direction of the slit, the two first auxiliary femaleelectrodes are arranged with the first auxiliary slit being sandwichedtherebetween in a short direction of the first auxiliary slit, therising substrate has a first auxiliary support portion and two firstauxiliary male electrodes provided in the first auxiliary supportportion, the first auxiliary support portion is inserted into the firstauxiliary slit, and the two first auxiliary male electrodes are solderedto the two first auxiliary female electrodes, respectively.
 10. Theprinted wiring board according to claim 9, wherein dimensions of thesupport portion and the slit in the longitudinal direction of the slitare respectively larger than dimensions of the first auxiliary supportportion and the first auxiliary slit in the longitudinal direction ofthe slit.
 11. The printed wiring board according to claim 9, wherein asurface area of the first auxiliary female electrode is larger than asurface area of each of the plurality of first electrodes, and a surfacearea of the first auxiliary male electrode is larger than a surface areaof each of the plurality of second electrodes.
 12. The printed wiringboard according to claim 1, wherein a height of upper ends of theplurality of second electrodes of the rising substrate is equal to orhigher than the top surface of the main substrate.